The invention relates generally to imaging of an object, and more specifically to volume based registration of two or more images.
Image registration finds wide application in medical imaging, video motion analysis, remote sensing, security and surveillance applications. Further, the process of finding the correspondence between the contents of the images is generally referred to as image registration. In other words, image registration includes finding a geometric transform that non-ambiguously links locations and orientations of the same objects or parts thereof in the different images. More particularly, image registration includes transforming the different sets of image data to a common coordinate space. The images may be obtained by different imaging devices or alternatively by the same imaging device but at different imaging sessions or time frames. As will be appreciated, in the field of medical imaging, there has been a steady increase in the number of imaging sessions or scans a patient undergoes. Images of a body part may be obtained temporally from the same imaging modality or system. Alternatively, in multi-modal imaging, images of the same body parts may be captured via use of different imaging modalities such as an X-ray imaging system, a magnetic resonance (MR) imaging system, a computed tomography (CT) imaging system, an ultrasound imaging system or a positron emission tomography (PET) imaging system.
In medical registration, registration of images is confronted by the challenges associated with patient movement. For example, due to either conscious or unconscious movement of the patient between two scans obtained either via the same imaging modality or otherwise, there exists an unpredictable change between the two scans. Unfortunately, this change in position leads to misalignment of the images. Additionally, patient position may vary depending on the imaging modalities used for multi-modal scanning. For example, a patient may be positioned in the prone position (i.e., lying face down) for a magnetic resonance imaging (MRI) scanning session of the colon and may be in the supine position (i.e., lying face up) during the same type of exam using a different piece of imaging equipment such as an ultrasound machine. The differences in position create inherent registration problems.
Volume-guided ultrasound is an application in which an ultrasound image is registered with a previously acquired (pre-acquired) image volume. The pre-acquired volume data set may include a CT image data set, an MR image data set, a PET image data set, or an ultrasound image data set, for example. Previously conceived solutions to effect the registration of the ultrasound image with the pre-acquired volume data set include use of a position sensing system having one or more sensors mounted on or in the ultrasound transducer. However, the process of registering the ultrasound image to the pre-acquired volume data set may be laborious and time-consuming.
There is therefore a need for a design of a method and system capable of efficiently registering an ultrasound image with a pre-acquired image volume data set obtained via a single modality or a plurality of imaging modalities. In particular, there is a significant need for a design of a method and a system for registering images that enhances workflow efficiency while minimizing errors.